So, your title tells us everything we need to answer your question in full. You had ZERO risk from oral sex. No details about who it was with, how it happened, how long, what happened after, symptoms you think you are having are necessary. It was no risk. The only risks for HIV are to have unprotected vaginal or anal intercourse or share IV needles to inject drugs. Air and saliva inactivate the virus and no one in the history of HIV, all these 40 plus years, has been proven or documented to get HIV from oral sex. So, this is no risk at all. No reason to test.